The present invention relates to a novel method of dehydrogenating cyclohexenone, more particularly, to a method of phenol synthesis by vapor-phase reaction using a solid-phase catalyst.
Dehydrogenation reaction of cyclohexenone has conventionally been accomplished by the following methods: (1) cyclohexenone is reacted with CuCl.sub.2 and LiCl to obtain phenol as described in J. Org. Chem., 28,633 (1963); and (2) cyclohexenone is reacted with CuBr.sub.2 and LiCl to obtain phenol as described in Tetrahedron Lett., 821 (1977).
These methods are based on a liquid-phase reaction and require after-treatment including the removal of catalysts. In addition, CuCl.sub.2 (or CuBr.sub.2) has to be used in two moles per mole of cyclohexenone, whereas LiCl has to be used in a molar amount equal to that of cyclohexenone. Therefore, from the viewpoint of cost-effect-evenness, the methods are very difficult to practice on a commercial basis. As a further problem, the yield of phenol that can be obtained is in the range of 65-85%, which is far from being satisfactory.